Oxidative stress triggers the preferential assembly of base excision repair complexes on open chromatin regions

Abstract

How DNA repair machineries detect and access, within the context of chromatin, lesions inducing little or no distortion of the DNA structure is a poorly understood process. Removal of oxidized bases is initiated by a DNA glycosylase that recognises and excises the damaged base, initiating the base excision repair (BER) pathway. We show that upon induction of 8-oxoguanine, a mutagenic product of guanine oxidation, the mammalian 8-oxoguanine DNA glycosylase OGG1 is recruited together with other proteins involved in BER to euchromatin regions rich in RNA and RNA polymerase II and completely excluded from heterochromatin. The underlying mechanism does not require direct interaction of the protein with the oxidized base, however, the release of the protein from the chromatin fraction requires completion of repair. Inducing chromatin compaction by sucrose results in a complete but reversible inhibition of the in vivo repair of 8-oxoguanine. We conclude that after induction of oxidative DNA damage, the DNA glycosylase is actively recruited to regions of open chromatin allowing the access of the BER machinery to the lesions, suggesting preferential repair of active chromosome regions.

Interaction with OGG1 Is Required for Efficient Recruitment of XRCC1 to Base Excision Repair and Maintenance of Genetic Stability after Exposure to Oxidative Stress

“…2 and 3). Those particular nuclear subdomains where OGG1 accumulates most likely represent regions where BER of 8-oxoG takes place (18,28). The data presented here demonstrate that the interaction of XRCC1 with the DNA glycosylase is necessary for the recruitment of the scaffolding protein to the BER pathway (6,22).…”

“…We have previously shown that after induction of oxidative DNA damage, OGG1 is recruited to chromatin, together with other BER proteins such as APE1, XRCC1, and LIG3 (18,28). The BER-specific recruitment of repair factors can be distinguished from the recruitment to SSBR through several criteria related to their relocalization within the nucleus: (i) the kinetics of formation of detergent-resistant foci or patches; (ii) their morphological parameters, such as size and circularity; and (iii) the requirement of PARP1 activity for their assembly.…”

“…XRCC1-YFP (YFP stands for yellow fluorescent protein) and OGG1-DsRED monomer plasmids used in this study have been previously described (28,29). The XRCC1(R194W)-YFP variant was obtained by site-directed mutagenesis of the XRCC1-YFP construct, using the QuikChange II XL site-directed mutagenesis kit (Stratagene).…”

Epigenetic reprogramming as a key contributor to melanocyte malignant transformation

“…The access-repair-restore theory proposed by Smerdon 54 showed that oxidative stress and other environment injuries can cause recruitment of DNA repair complexes preferentially to open chromatin regions. [55][56][57] Additionally, an opened chromatin configuration caused by DNA damage might explain the "stem cell like" characteristics identified in pre-malignant 4C cells. The repair factors could then recruit chromatin remodeling proteins, histone modifying enzymes as well as DNMTs to DNA lesion in order to repress transcription and stop possible sequence reading errors.…”

Recognition of Damaged DNA: Structure and Dynamic Markers

“…47,48 There is clear evidence that the chromatin structure can hinder the initial steps of BER. 49,50 Although glycosylase activity (UNG2 and SMUG1) is indeed reduced on reconstituted nucleosomes, the complete BER cascade, including APE1, Polb, and DNA ligase III was found to be functional. 44 Recently it was shown that UDG and APE1 are able to interact with an uracil in a nucleosomal construct when the lesion is accessible from the outside, but recognition is hampered if the lesion is shielded by the histone core.…”